Process for preparing dyes useful as sensitizers for silver halide emulsions



United States Patent 3,506,655 PROCESS FOR PREPARING DYES USEFUL AS SENSITIZERS FOR SILVER HALIDE EMULSIONS Roy Arthur Jetfreys, Middlesex, England, assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Jan. 3, 1966, Ser. No. 518,010 Claims priority, application Great Britain, Jan. 7, 1965,

789/65 Int. Cl. C09b 23/00; G03c 1/10 U.S. Cl. 260240.1 7 Claims ABSTRACT OF THE DISCLOSURE Styryl, hemicyanine, merocyanine, complex, oxamine and other cyanine dyes useful as sensitizers for photographic silver halide emulsions are prepared by reacting certain enamine compounds with an amino substituted aldehyde, a 2-alkylthioheterocyclic quaternary salt, a 2- (2-acetanilidovinyl) heterocyclic quaternary salt, a 2- (4-acetanilidoubutadienyl) heterocyclic quarternary salt, an alkoxymethylene derivative of a ketomethylene heterocyclic compound or ethylisoformanilide.

Styryl, hemicyanine, merocyanine and complex dyes are known types of photographic silver halide sensitizing dyes. These dyes are usually made by condensing a suitable cyclammonium quaternary salt with an appropriate intermediate under suitable conditions. For example the synthesis of certain styryl dyes is described by Brooker et al. U.S. Patent 2,494,032 issued Jan. 10, 1950, the synthesis of certain hemicyanine dyes is described by White U.S. Patent 2,369,509 issued Feb. 13, 1945, and the synthesis of certain merocyanines is described by Aubert and Knott U.S. Patent 2,652,397 issued Sept. 15, 1953. These reactions are usually conducted in a suitable solvent in the presence of a basic condensing agent and at a temperature between room temperature and the reflux temperature of the solvent in the reaction mixture.

Oxamine (e.g. hemioxonol) and cyanine dyes wherein the meso carbon atom is substituted with an amino group are also known types of photographic silver halide sensitizing dyes. The synthesis of certain hemioxonol dyes is described in Keyes U.S. Patent 2,186,608 issued Jan. 9, 1940. The synthesis of certain cyanine dyes wherein the meso carbon atom is substituted with an amino group is disclosed in British Patents 684,650 and 719,238.

New methods for preparing photographic sensitizing dyes are desirable. Therefore, it is an object of my invention to provide a new process for preparing styryl, hemicyanine, merocyanine, other cyanine, complex and oxamine photographic sensitizing 'dyes.

Another object is to provide a process for preparing dyes 'which comprises reacting an enamine compound with a compound selected from the group consisting of an amino substituted aldehyde, a 2-alkylthioheterocyclic quaternary salt, a 2-(Z-acetanilidovinyl)heterocyclic quaternary salt, a 2-(4-acetanilidobuta'dienyl)heterocyclic quaternary salt, an alkoxyrnethylene derivative of a ketomethylene heterocyclic compound and ethylisoformilide.

Another object is to provide photographic sensitizing dyes made by the process of my invention.

A further object is to provide new photographic silver halide emulsions.

Other objects will become evident from a consideration of the following specification and claims.

The enamines used in the process of my invention have the formula:

(I) CHRz wherein R is a hydrogen atom or an alkyl group,

R is an alkyl group, or

R and R together complete a carbocyclic ring,

R and R each independently-represent an alkyl, a substituted alkyl, an aryl or a substituted aryl group, or together represent the non-metallic atoms necessary to complete a 5- or 6-membered heterocyclic ring.

N-cyclopentenylpyrrolidine 1-[-cyclopenten-1-yl] pyrrolidine) N-cyclohexenylpyrrolidine 1-[ l-cyclohexenl-yl] pyrrolidine N-cyclopentenylpiperidine ll-cyclopentenl-yl] piperidine) N-cyclohexenenylpiperidine 1- l-cyclohexenl-yl] piperidine N-cyclopentenylmorpholine 1-[ l-cyclopentenl-yl] morpholine) and N-cyclohexenylmorpholine 1-[ l-cyclohexen-l-yl] morpholine for example, is condensed with the quaternary salts just mentioned hernicyanines having the formula:

(III) wherein R represents an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl or hexyl, for example, allyl, and a substituted alkyl group such as B-hydroxyethyl, B-hydroxypropyl, -hydroxypropyl, a-hydroxy- 3 4 butyl, fl-acetoxyethyl, fl-sulfoethyl, sulfopropyl, sulfobutyl pound employed is N-cyclohexenylpyrrolidine the oxor ethoxycarbonylmethyl, n represents 1 or 2, X repreamine dye compounds obtained have the formula: sents an acid anion such as the chloride, bromide, iodide, (v) methyl sulfate, ethyl sulfate, thiocyanate, sulfonate, perchlorate, p-toluenesulfonate, benzenesulfonate, etc. and 5 Z represents the non-metallic atom necessary to complete N t i C a heterocyclrc nucleus containing from five to SIX atoms W in the heterocyclic ring, such as those selected from the group consisting of the thiazole series [c.g. thiazole, 4-

methylthiazole, 4-phenylthiazole, S-methylthiazole, 5- 1O phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, 4-(2-thienyl)thiazole, etc.], those of the benzothiazole Wherelh has hf e prevlousllf asslghed to series (e.g. benzothiazole, 4-chlorobenzothiazole, S-chloro- The ehamlhe group lolhed 9 the methlhe carbon atom benzothiazole, 6-chlorobenzothiazole, 7-chlorobenzothiathrough the Carbon at m sharlng the double bond of the zole, 4-methylbenzothiazole, S-methylbenzothiazole, '6- 15 eylelopehtehyl. 0T cycltfhexehyl nucleus Whleh, P to methylbenzothiazole, S-bromobenzothiazole, 6-brornobenthe eehdehsatlon TeaetlOIl, s a slngle hydrogen atom zothiazole, 4-phenylbenzothiaz0le, S-phenylbenzothiazole, attached thereto- 4-methoxybenzothiazole, S-methoxybenzothiazole, 6-meth- As Shown herelhefter the enamine compohhds F be oxybenzothiazole, S-iodobenzothiazole, 6-iodobenzothiaconverted to lmmohlllm a s by treatment with acids and zole, 4-ethoxybenzothiazole, S-ethoxybenzothiazole, tetra- Subsequently fiohdehsed thlS State Wlth Intermediate hydrobenzothiazole, 5,6-dimethoxybenzothiazole, 5,6-di- Peh heelosed herelhatter to form photographlc oxymethylenebmzothiazole, ShYdroXYbenZothiazole sensltlzlng dye compounds. Such condensatlons are prefhydroxybenzothiazole, etc.), those of the oxazole series f y earned out In t P e of a hasle e0hdeh5a- (e.g. 4-methyloxazole, 5-methyloxazole, 4-phenyloxazole, tloh catalyst Such a trlethylamlhe- 4 5 di 4 ethyloxazole 45 dimethyloxazole, When an enamine compound having the Formula I 5-phenyloxazole,etc.),those of the benzoxazole series (e.g. 1S Converted to he lmrhohmm Salt condensed with benzoxazole, S-chlorobenzoxazole, S-methylbenzoxazole, one mole of an aromatle aldehyde havlhg the formula:

S-phenylbenzoxazole, 6-methylbenzoxazole, 5,6-dimethyl- (VI) R5 benzoxazole, 4,6-dimethylbenzoxazole, S-methoxybenzox- (OH=OH)m CHO azole, S-ethoxybenzoxazole, S-chlorobenzoxazole, 6methoxybenzoxazole, S-hydrobenzoxazole, 6-hydroxybenzoxa- R5 zole, etc.), those of the thiazoline series (e.g. thiazoline, wherein each 5 Independently fepresehts an alkyl group 4-methylthiazoline, etc.) are obtained. such as methyl, ethyl, p p p py y lsobutyl, The condensation reaction using the enamine comy or hexyl, for example, or a y y y group pounds having the Formula I is preferably carried out by Such as Y Y YL F' Y YP PY Y' Y YP heating the reactants in an inert solvent, such as ethanol Py ehydfoxyhutyl, fOr p and m is or acetic anhydride, in the absence of any basic comastyry y having the formula:

P v11 R3 In Hemicyanine compounds corresponding to those represented by Formula III can also be prepared by the 6 use of another enamine compound, such as those specif- /N tCH=CH)m CH:$*C CH2R2X ically named hereinbefore, for example. R Rt As noted hereinbefore in accordance with the process is obtained of y invention an enamine Compound having the When an enamine having the Formula I is converted mule I can be Condensed With an alkoxymethylene derivato its immonium salt and condensed with two moles of tive of a ketomethylene heterocyclic compound to form an aromatic aldehyde having the Formula VI, a complex oxamine dye compounds. When N-cyclopentenylpyrrolistyryl dye having the formula:

(VIII) Rs Rt Ra R5 R2 R5 dine is the enamine employed oxamine dye compounds wherein R R R R in and X have the meaning prehaving the formula: viously assigned to them, R represents an alkyl group and (IV) wherein LN) =C-ll-CHR2 (:0 W

i I =CH {W collectively can be a cyclopentylidene of a cyclohexylidene nucleus, is obtaind. wherein W represents the non-metallic atoms necessary The preparatloh 0f y y lf having the Formula to complete a S-membered heterocyclic ring selected from VII by e01'1deh SlI1g an enamine ll'hmohiuhl t h One the class consisting of a 4-oxothiazolidine compound and molar p p f h of an at0h1atle aldehyde having the a 2 1 compound are Obtained Formula VI is illustrated in Example 12. The preparation When other enamine compounds having the Formula of Complex y y y having the Formula VIII y I, such as those specifically named, are condensed with (lensing an enamine immonium Salt with two molar P an alkoxymethylene derivative of a ketomethylene heteropo tions f an ar matic aldehyde having the Formula VI cyclic compound instead of N-cyclopentenylpyrrolidine is illustrated in Example 19. oxamine dye compounds corresponding to those of For- In accordance with the process of my invention the mula IV, but in which the enamine compound is ditfcrenamine compounds in immonium salt form can be conent, are obtained. To illustrate when the enamine corndensed, a basic catalyst being present in the reaction mixture, with a 2-alkylthioheterocyclic quaternary salt having the formula:

a 2-(Z-aeetanilidovinyl)heterocyclic quaternary salt having the formula:

or a 2-(4-acetanilidobutadienyl)heterocyclic quaternary salt having the formula:

wherein R, Z and X have the meaning previously assigned to them and R represents an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl or hexyl, for example, to form hemicyanine dyes which when an immonium salt of N-cyclopentenylpyrrolidene is the enamine compound employed have the Formula III.

As previously stated the enamine compounds having the Formula I can be condensed with a 2-alkylthioheterocyclic quaternary salt, a 2-(Z-acetanilidovinyl)heterocyclic quaternary salt or a 2-(4-acetanilidobutadienyl)heterocyclic salt, which have the Formulas IX, X and XI, respectively to form hemicyanine dyes.

Similarly in accordance with the process of my invention the enamine compounds in their immonium salt form, a basic catalyst being present in the reaction mixture, or non-salt form can be condensed with an alkoxymethylene derivative of a ketomethylene heterocyclic compound such as those having the formula (XII) 43:0

-C=CHOR9 or an acetanilido-methylene derivative of a heterocyclic compound, such derivative having the formula:

(XIII) ,-O=O

-C=CHN-Ph O=C CH3 wherein W has the meaning previously assigned to it and R represents an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl or hexyl, for example, to form oxamine compounds having the formula;

wherein W, R R R and R have the meaning previously assigned to them.

As only a limited number of alkoxymethyl derivatives of heterocyclic compounds having a ketomethylene group are available, an alternative two stage synthesis may be used. In this method the enamine immonium salt is first reacted with one molar proportion of ethylisoformanilide to give an intermediate having the formula:

which can be acylated (e.g. acetylated) or used directly in the presence of acetic anhydride with ketomethylene heterocyclic compounds to form oxamine dye compounds, or with heterocyclic quaternary salts having a reactive methyl group to form hemicyanine dye compounds.

If two molar proportions of ethylisoformanilide are reacted with the enamine immonium salt an intermediate having the formula:

(XVI) R3 R4 wherein R R R and X have the meaning previously assigned to them and R represents an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl or hexyl for example, is obtained. This compound or its acetylated derivative reacts with a heterocyclic quaternary salt having a reactive methyl group to form symmetrical cyanine dyes.

The oxamine dye compounds formed as described herein which possess a 2-thio substituent can be alkylated with an alkyl ester in known fashion and further condensed to provide complex dyes such as those having the formulas:

wherein R, R R R R W and Z have the meaning previously assigned to them, n is 0 or 1 and R represents an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl or hexyl, for example, and a substituted alkyl group such as B-hydroxyethyl, B-hydroxypropyl, 'y-hydroxypropyl, B-hydroxybutyl, fl-acetoxyethyl, B-sulfoethyl, sulfopropyl and sulfobutyl, for example, using the oxamine derived from rhodanine.

Merocyanine dyes derived from rhodanine and analogous thiones can be alkylated, in general, and condensed with the immonium salts of the enamines to give complex dyes. In the case of the perchlorate immonium salt of N- cyclopentenylpyrrolidine a dye is obtained having the formula:

(XIX) O=C-N-R z o= oH-o )..z=o

(XX) R CHRz wherein R R and R have the meaning previously assigned to them and R represents a hydrogen atom, an alkyl group such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, amyl or hexyl, for example, or with R represents the atoms necessary to complete a carbocyclic ring, it can react with two moles of a dye intermediate such as those having the formulas designated IX, X and XI, in acetic anhydride with sodium acetate to give the symmetrical cyanine dyes having the Formula XXI, The enamine may be condensed per se or as its immonium salt.

(XXI) R3 R4 wherein R, R R R R Z, n and X have the meaning previously assigned to them.

Similarly, unsymmetrical cyanine dyes can be prepared by first condensing the enamine per se or in its immonium salt form with a heterocyclic quaternary salt intermediate, such as those having the formulas designated IX, X, and XI to form a hemicyanine dye and then condensing the hemicyanine dye with a second intermediate such as a different heterocyclic quaternary salt intermediate, such as those having the formulas designated IX, X and XI, to form the cyanine dye.

Styryl dyes such as those having the Formula VII can be reacted with dye intermediates having an electrophilic carbon atom, such as the heterocyclic quaternary salts having the Formulas IX, X and XI, for example, to produce complex styryl dyes having the formula:

wherein R, R R R R R Z, m, n and X have the meaning previously assigned to them. Many of the styryl dyes having the formula just given are powerfully supersensitized by compounds such as Leucophor B. Other complex styryl dyes, i.e. those having the Formula VIII are disclosed herein,

Particularly useful dyes are obtained using the enamine N-cyclopentenylpyrrolidine per se or in its immonium salt form and my invention is particularly directed to the use of this enamine compound in the process of any invention. Many of the dye compounds obtained by the use of this enamine compound are powerful sensitizers for photographic gelatino-silver halide emulsions.

The dye compounds prepared in accordance with my invention sensitize photographic gelatino-silver halide emulsions, such as silver chloride, silver chlorobromide and silver bromoiodide emulsions, to as high as 790 m The results obtained using various dye compounds prepared in accordance with the process of my invention are set forth in the examples.

The following examples further illustrate my invention. The preparation of enamine immonium salts and the preparation of dyes and dye intermediates according to the invention using the enamines or their immonium salts is illustrated in the following examples.

EXAMPLE 1 N-cyclopentylidenepyrrolidinium perchlorate ClOr Perchloric acid (33 ml. of 60% aqueous solution) was added slowly to a cooled stirred solution of N-cyclopentenylpyrrolidine (27.4 grams) in acetone ml.). The reaction mixture was allowed to reach room temperature, after which ether (25 ml.) was added, and the product was filtered off. It was obtained as colorless leaflets from ethanol in 32 grams (67%) yield, M.P. 229- 231.

EXAMPLE 2 N- (2-anilinomethylenecyclopentylidene) pyrrolidinium perchlorate CHNHPH The compound of Example 1 (20.0 grams) and ethylisoformanilide (14.5 grams) were fused together by heating at for /2 hour. The cooled product was stirred with acetone, and then filtered otf. It was recrystallized from methanol-ether as orange prisms, M.P. 210, in 25 grams (87%) yield.

EXAMPLE 3 3-ethyl-5- [2-( l-pyrrolidinyl) cyclopentenylmethylene] rhodanine N-cyclopentenylpyrrolidine (4.1 grams) and 5-ethoxymethylene-3-ethyl-4-oxo-2-thionothiazolidine (6.5 grams) were warmed in ethanol (30 ml.), and after the reaction was complete the reaction mixture was cooled to effect precipitation of the dye product formed. The dye product was recrystallized from benzene in the form of maroon prisms, M.P. 226 C., in 5.7 grams (62%) yield. The dye compound thus obtained sensitized silver chlorobromide and bromoiodide emulsion to 640 mg with peaks at 570 mg.

This dye was also prepared in 52% yield by heating (in the molar proportions indicated) the intermediate of Example 2 (1 mol), 3-ethyl-4-oxo-2-thionothiazolidine (1 mol), acetic anhydride (1 mol) and triethylamine together (2 mol) in ethanol.

EXAMPLE 4 3-ethyl-2- [2-( l-pyrrolidinyl cyclopentenyl] benzothiazolium iodide N-cyclopentenylpyrrolidine (2.7 grams) and 3-ethyl-2- ethylthiobenzothiazolium-p-toluenesulfonate (7.9 grams) in ethanol (25 ml.) were refluxed together for 10 minutes. The reaction solution was poured into excess aqueous sodium iodide, and the product separated. It was recrystallized from ethanol-ether as chunky orange-brown prisms, M.P. 243244 C. (decomp.), in 2.4 grams (28%) yield.

9 EXAMPLE 3 -ethyl-2-{2- [2- l-pyrrolidinyl) cyclopentenyl] vinyl} benzoxazolium iodide N-cyclopentenylpyrrolidine (2.7 grams) and 2-[2- acetanilidovinyl1-3 ethyl benzoxazolium iodide (8.7 grams) in ethanol (35 ml.) were refluxed together for minutes after which the reaction mixture was chilled to precipitate the dye product formed. The dye product was filtered oc from the chilled solution. After several recrystallizations fro methanol it wacs obtained as bright blue prims, M.P. 299 'C. (decomp.) in 4.8 grams (55%) yield. The dye thus obtained sensitized silver chlorobromide and bromoiodide emulsions to 560 mu with peaks at 515 my.

EXAMPLE 6 3-ethyl-2-2 [2- l-pyrrolidinyl cyclopentenyl] vinylbenzothiazolium iodide N-cyclopentenylpyrrolidine (2.7 grams) and 2-[2- acetanilidovinyl] 3 ethylbenzothiazolium iodide (9 grams) in ethanol (25 ml.) were shaken together at room temperature for /2 hour. The dye product formed was filtered off and recrystallized from ethanol to remove magenta and blue impurities. The orange dye was obtained as maroon leaflets, M.P. 297-299 C. with decomp. (darkens at 290 C.) in 2.1 grams (23%) yield.

EXAMPLE 7 Bis-(3-ethyl-2-benzothiazo1e)-'y,e-ethylene-6- pyrrolidinvl heptamethinecyanine iodide \lllj S I C=CHCH=QC=CCH=CH-C CH2CHz N (IL2H5 CzHa 10 EXAMPLE 8 2 (3 ethoxycarbonylmethyl-4-oxo-2-thioxo-5-thiazolidinylidene) 3 ethyl-5-{[2-(1-pyrrolidinyl)cyclopentenyl]methylene}-4-thiazolidinone The dye of Example 3 (1.5 grams) and dimethyl sulfate (1 ml.) were heated on the steam-bath for 1 hour. To the mix were added 3-ethoxycarbonylmethyl-4-oxo-2- thioxothiazolidine (1.1 grams) and triethylamine (0.7 ml.) in ethanol (12 ml.). The resulting solution was refluxed for 10 minutes and then chilled to precipitate the dye product formed. The dye product was filtered off, washed with ethanol and then with acetone, and recrystallized from pyridine-ethanol as green microcrystals, M.P. 28l283 C. (decomp.), in 1.4 grams (58%) yield. The dye compound thus obtained sensitized a silver chlorobromide emulsion to 680 m l with a peak at 630 mu.

EXAMPLE 9 2 (3 ethoxycarbonylmethyl-4-oxo-2-thioxo-5-thiazo1idinylidene ethylidene) -3-ethyl-5-{ [2-( 1-pyrrolidinyl)- cyclop entenyl] methylene} -4-thiazolidinone The dye of Example 3 (1.5 grams) and methyl sulfate (1 ml.) were heated on the steam-bath for 1 hour. To the mix were added 3-ethoxycarbonylmethyl-S-ethy1idene-4- oxo-2-thioxothiazolidine (1.2 grams) and triethylamine (0.7 ml.) in ethanol (12 ml.). The solution was refluxed for 10 minutes and chilled. The product was filtered off, washed With ethanol and then with acetone, and recrystallized from puridine-ethanol as green microcrystals, M.P. 254 C., in 0.5 gram (20%) yield.

EXAMPLE 10 3 ethyl 2 (3 ethyl-2-benzothiazolin-ylidenemethyl)- 5-[2-(1-pyrrolidinyl) cyclopentenylmethylene]-2 thiazolinium iodide The dye of Example 3 (1.5 grams) and methyl sulfate (1 ml.) were heated on the steam-bath for 1 hour. To the mix were added 3-ethyl-2-methylbenzothiazolium iodide (1.5 grams) and triethylamine (0.7 ml.) in ethanol (12 ml.). The solution was refluxed for 10 minutes and then chilled to precipitate the dye compound formed. The dye product was filtered oil, washed with ethanol, acetone and ether, and then recrystallized from methanol-ether as metallic green prisms, M.P. 286 C. (decomp.), in 1.6 grams (55%) yield. The dye compound thus obtained sensitized a silver bromoiodide emulsion to 660 m with a peak at 620 mp.

EXAMPLE 1 1 2 (2 dicyanomethylene 3 ethoxycarbonylmethyl-4- oxothiazolid 5-ylidene)-3-ethyl-5-[2-(1-pyrrolidinyl)- cyclop entenylmethylene] thiazolid-4-one The dye of Example 8 (0.5 gram) and methyl sulfate (0.5 ml.) were heated on the steam-bath for 1 hour. To the mix were added malononitrile (0.07 gram) and triethylamine (0.14 ml.) in ethanol (10 ml.). The resulting solution was refluxed for 10 minutes, and chilled to precipitate the dye compound formed. The dye product was filtered oif, washed with ethanol and then with acetone, and recrysallized from pyridine-ethanol as bright green needles, M.P. above 330 C., in 0.2 gram (38%) yield. The dye compound thus obtained sensitized a silver chlorobromide emulsion to 660 mu with a peak at 610 m z, and a silver bromoiodide emulsion with a peak at 590 m EXAMPLE 12 N-{2- (4-dimethylaminobenzylidene cyclopentylidene} pyrrolidinium perchlorate EXAMPLE l3 3 ethyl 5-[(3-ethyl-2benzothiazolinylidene)ethylene]- 4 oxo 2-[2-(l-pyrrolidinyl)cyclopentenyl]-2-thiazolinium perchlorate 3 ethyl-5-(3-ethylbenzothiazolin-2-ylidene-ethylidene- 4-oxo-2-thioxothiazolidine (0.87 gram) and methyl sulphate (0.8 ml.) were heated together on a steam-bath for /2 hour. To the mixture thus obtained were added N- cyclopentenylpyrrolidine (0.35 gram) and ethanol (15 12 ml.). The resulting solution was refluxed for /1 hour, then cooled and excess aqueous sodium perchlorate was added to the cooled solution. The dye product formed was filtered off and recrystallized from pyridine-ethanol as red needles, M.P. 303 C. (decomp.), in 0.25 gram (15%) yield. The dye compound thus obtained sensitized a silver chlorobromide emulsion to 620 m with a peak at 575 mp.

EXAMPLE 14 N-(Z-acetanilidomethylenecyclopentylidene)pyrrolidinium perchlorate A mixture of the compound of Example 2 (1 gram), in acetic anhydride (15 ml.) was refluxed for 20 minutes. The solution was cooled and a little ether (3 ml.) was added. The dye product formed was filtered off and recrystallized from ethanol as straw needles, M.P. 204 C., in 0.8 gram (71%) yield.

EXAMPLE 15 N-(2,5-dianilinomethylenecyclopentylidene) pyrrolidinium perchlorate a ll PhNHCH- |=CHNHPh C104 From the preparation of Example 2, when the crude product was dissolved in methanol-ether for recrystallization, there was a rather insoluble residue, insoluble residue (N- 2,5-dianolinomethylenecyclopentylidene] pyrrolidinium perchlorate) was recovered and recrystallized from pyridine-methanol as orange needles, M.P. 270- 274 C. with decomposition, in 4 gram yield. It could be obtained in much better yield in an alternative synthesis by using 2-moles of ethylisoformanilide in the reaction of Example 2.

EXAMPLE 16 N-(2,S-diacetanilidomethylenecyclopentylidene) pyrrolidinium perchlorate OHN NCH

COCH;

13 EXAMPLE 17 3-ethy1-5-(3-methyl-2-pyrrolidin-1'-ylcyclohexen'- ylmethylene -2-thiothiazolid-4-one N-6-methylcyclohexenylpyrrolidine (4.9 grams) and S-ethoxymethylene 3 ethyl-2-thi0thiazo1id-4-one (6.5 grams) were warmed together in ethanol (30 ml.) for 10 minutes, and water (5 ml.) was added. The reaction mixture was cooled and the dye product formed was filtered oil from the chilled solution, washed with ethanol and water, and recrystallized from ethanol, and then from light petroleum. It was obtained as red platelets, M.P. 139 C., in 5.8 grams (58%) yield. The dye compound thus obtained sensitized a silver chlorobromide emulsion to 630 m with a peak at 580 mu, and a bromoiodide emulsion to 650 m with a peak at 5 80 III/L.

EXAMPLE 1 8 3 -ethyl-5- (2 -morpholinocyclohexenyl methylene- 2-thiothi azolid-4-one l O=CNC2H5 CH: C=S

N-cyclohexenylmorpholine (1.7 grams) and S-ethoxymethylene 3 ethyl-2-thiothiazolid-4-one (2.2 grams) in acetic anhydride (12 ml.) were refluxed together for 10 minutes, and the resulting solution was chilled. The dye product formed was filtered off, washed with ethanol, and recrystallized from ligroin as red needles, M.P. 175 C., in 2.0 grams (59%) yield. 3-ethyl-S-morpholinomethylene-2-thiothiazolid-4-one was left as a residue from the ligroin solution of the product.

The dye compound thus obtained sensitized a silver N cyclopentylidenepyrrolidinium perchlorate (2.4 grams) and p-dimethylaminobenzaldehyde (4 grams) in acetic anhydride (30 ml.) were refluxed together for 15 minutes after which the reaction solution was cooled. Ether was added to the cooled solution to precipitate the reaction product. The dye product thus obtained was washed with methanol and recrystallized from acetic acid as bronze leaflets, M.P. 275 C., in 1 gram (20%) yield.

The dye compound thus obtained sensitized a silver chlorobromide emulsion to 680 m with a peak at 610 m and a silver bromoiodide emulsion to 650 my. with a peak at 610 III/1..

EXAMPLE 20 N-[2,5-di-(4-dimethylaminocinnamylidene)clclopentylidene]pyrrolidinium perchlorate N --CH=OHCH CHOH=CH N 0104 N cyclopentylidenepyrrolidinium perchlorate (1.2

grams) and p-dimethylaminocinnamaldehyde (1.8 grams) in acetic anhydride (20 ml.) were refluxed together for 10 minutes. The reaction mixture was cooled and the reaction product was filtered off from the cooled reaction mixture, washed with acetic anhydride and ether, and recrystallized from pyridine-ether as a dull bronze powder, M.P. 198 C. (decomp.), in 1.7 grams (62%) yield.

EXAMPLE 21 2-phenyl-4-(2-pyrrolidin-1-ylcyclopentenylmethylene)- 2-oxazolin-5-one lQ-Cl N [2 (6 dimethylaminobenzylidene) 5 (3 ethylbenzoxazolin 2 ylidene ethylidene)cyclopentylidene] pyrrolidinium perchlorate N [2 (4 dimethylaminobenzylidene)cyclopentylidene]pyrrolidinium perchlorate (Example 12) (1.2 grams) and 2 [2 acetanilidovinyl] 3 ethylbenzoxazolium iodide (1.4 grams) with sodium acetate (0.3 gram) in acetic anhydride (15 ml.) were refluxed together for 10 15 minutes. The dye product formed was filtered off, washed, and recrystallized from methanol as glossy sepia needles, M.P. 238 C., in 0.4 gram (23%) yield. The dye compound thus obtained sensitized a silver chlorobromide emulsion to 710 m with a peak at 630 me, and a silver bromoiodide emulsion to 670 m with a peak at 620 III/L. Supersensitization with Leucophor B extended the silver chlorobromide sensitization to 740 m with a peak at 640 m EXAMPLE 23 N- [2 (4 dimethylaminobenzylidene) 5 (3 ethylbenzothiazolin 2 ylidene ethylidene)cyclopentylidene]pyrrolidinium perchlorate N [2 (4 dimethylaminobenzylidenecyclopentylidene]pyrrolidinium perchlorate (Example 12) (1.2 grams) and 2 [2 acetanilidovinyl] 3 ethylbenzothiazolium iodide (1.5 grams) with sodium acetate (0.3 gram) in acetic anhydride (15 ml.) were refluxed together for minutes. The dye product formed was filtered ofi', washed, and recrystallized from ethanol-ether as sepia needles, M.P. 250 C., in 0.5 gram (28%) yield.

The dye compound thus obtained sensitized a silver chlorobromide emulsion to 720 mp. with peaks at 630 and 680 mg, and was supersensitized by Leucophor B to give sensitization to 770 m with a peak at 680 mp.

The foregoing examples are intended to be illustrative and not limitative of my invention. Thus while the process of my invention has been illustrated primarily with reference to the use of N-cyclopentenylpyrrolidine it will be understood that any of the other enamine compounds, such as the other 6 enamine compounds specifically named herein can be used in place of N-cyclopentenylpyrrolidine. This would apply to Examples 1, 3, 4, 5, 6, 7, 12, 13, 19, 20 and 21, for example. Likewise the other enamine compounds, such as those specifically disclosed, can be used in place of the particular enamine compounds employed in Examples 17 and 18.

Ethanol, propanol, isopropanol, 1,4-dioxane, pyridine and quinoline are illustrative of the inert organic solvents that can be used to advantage in carrying out the process of my invention. Basic condensation catalysts or agents that can be employed in the condensation of an enamine immonium salt with an intermediate to form a dye include organic tertiary amines, such as the trialkylamines, e.g., triethylamine, tripropylamine, triisopropylarnine, tributylamine, etc., the N,N dialkylanilines, e.g., N,N-dimethylaniline, etc., the N-alkylpiperidines, e.g., N-methylpiperidine, N-ethylpiperidine, etc.

The sensitizing dyes described herein are used to advantage in manufacturing photographic silver halide emulsions, serving to alter the sensitivity thereof. The type of silver halide emulsions that are sensitized with my dyes include any of those prepared with hydrophilic colloids that are known to be satisfactory for dispersing silver halides, for example, emulsions comprising materials such as, gelatin, albumin, agar-agar, gum arabic, alginic acid, etc., and hydrophilic synthetic resins such as polyvinyl alcohol, polyvinyl pyrrolidone, cellulose ethers, partially hydrolyzed cellulose acetate and the like.

In the preparation of photographic emulsions, the dyes are advantageously incorporated in the finished silver halide emulsion and should, of course, be uniformly distributed throughout the emulsion. The methods of incorporating dyes in emulsions are relatively simple and well known to those skilled in the art of emulsion making. For example, it is convenient to add the dyes from solutions in appropriate solvents, in which case the solvent selected should be completely free from any deleterious eflect on the ultimate light-sensitive materials.

The concentration of the dyes in the emulsion can be varied widely, i.e., from about 5 to about mg. per liter of fiowable emulsion. The specific concentration will vary according to the type of light-sensitive material in the emulsion and according to the effects desired. The suitable and most economical dye concentration for any given emulsion will be apparent to those skilled in the art upon making the tests and observations customarily used in the art of emulsion making.

To prepare a gelatino-silver halide emulsion sensitized with one of the sensitizing dyes disclosed herein, the following procedure is satisfactory: A quantity of the dye is dissolved in a suitable solvent and the volume of this solution containing from 5 to 100 mg. of dye is slowly added to about 1000 cc. of the gelation-silver halide emulsion. With most of the dyes, 10 to 20 mg. of dye per liter of emulsion sufiice to produce the maximum sensitizing effect with the ordinary gelatino-silver bromide (including bromoiodide and chlorobromide) emulsions. With fine grain emulsion, which include most of the ordinarily employed gelation-silver chloride emulsions, somewhat larger concentrations of the dye may be necessary to secure optimum sensitizing elfect, while the preceding has dealt with gelatino emulsions, it will be understood that these remarks apply generally to any emulsions wherein part or all of the gelatin is replaced by another suitable hydrophilic colloid such as mentioned above.

The above statements are only illustrative and are not to be understood as limiting the invention in any sense, as it will be apparent that the dyes can be incorporated by other methods in many of the emulsions employed in the art. For instance, the dyes can be incorporated by bathing a plate or film upon which the emulsion has been coated, in the solution of the dye in an appropriate solvent.

Although the invention has been described in considerable detail with particular reference to certain preferred embodiments thereof, variations and modifications can be effected within the spirit and scope of the invention as described hereinbefore and as defined in the appended claims.

I claim:

1. A process for making dyes which consists essentially of reacting a mixture of (1) a compound selected from the enamine compounds N-cyclopentenylpyrrolidine, N- cyclohexenylpyrrolidine, N- cyclopentenylpiperidine, N- cyclohexenylpiperidine, N-cyclopentenylmorpholine, N- cyclohexenylmorpholine and the immonium salt form of said enamine compounds 2. basic catalyst being present in the reaction mixture when said immonium salts are employed and (2) a compound selected from the class consisting of those having the formulas:

R-N=c-sR1 x wherein R represents a member selected from the class consisting of an alkyl group having 1 to 6 carbon atoms,

allyl, a monohydroxyalkyl group having 2 to 4 carbon atoms, ;9- acetoxyethyl, flsulfoethyl, sulfopropyl and ethoxycar-bonylmethyl, R, represents an alkyl group hav- 1 8 dine or its immonium salt form and the second reactant is a compound having the formula designated 4.

6. A styryl dye compound having the general formula:

ing 1 to 6 carbon atoms, R represents an alkyl group 10 wherein each R independently represents a member having 1 to 6 carbon atoms, W represents the nonmetallic atoms necessary to complete a S-membered heterocyclic ring selected from the class consisting of a 4-oxothiazolidine compound and a 2-oxazolin-5one compound, Z represents the nonmetallic atoms necessary to complete a heterocyclic nucleus selected from the class consisting of a thiazole nucleus, a benzothiazole nucleus, an oxazole nucleus, a benzoxazole nucleus, a thiazoline nucleus and a thiazolidine nucleus, m is 0, 1 or 2, n is 1 or 2 and X is an acid anion, in an inert Organic solvent and wherein the temperature ofthe reaction mixture is maintained in the range from room temperature to the reflux temperature of the reaction mixture throughout the reaction.

2; A process in accordance with claim 1 wherein the enamine compound employed is N-cyclopentenylpyrrolidine or its immonium salt form and the second reactant I selected from the class consisting of an alkyl group having 1 to 6 carbon atoms and a monohydroxyalkyl group having 2 to 4 carbon atoms, Q represents the non-metallic atoms necessary to complete a member selected from the class consisting of pyrrolidyl, piperidyl and morpholinyl, Q represents the non-metallic atoms necessary to complete a member selected from the class consisting of the cyclopentylidene nucleus and the cyclohexylidene nucleus, In represents 0, 1 or 2 and X represents an acid anion.

7. The compound pyrrolidinium perchlorate.

References Cited UNITED STATES PATENTS 3,177,116 4/1965 Wood et a1 260-240 XR 3,179,559 4/1965 Wood et a1 260-240 XR OTHER REFERENCES Birkofer et al., Chem. Ber., vol. 95, pp. 1495 to 1504 (1962).

Paquette, Tetrahedon Letters, No. 18, pp. 1291 to 1294 1964) JOHN D. RANDOLPH, Primary Examiner US. Cl. X.R.

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Potent: No. 3506655 Dated April 1 127;

Inventor) Roy A. Jeffreys PAGE 1 It is cattified that error appears in the above-identified patent and that said Lettatl Patent are hureby corrected as shown below:

should read Column 6, line 27 "(XVIII)" should read --(XVII)--,

Patent No. 3506655. Dated April 1 1970 Inventor(s) Roy A, Jeffre PAGE 2 It is certified that error appears in the ebove-ident1fied patent and that said Letters Patent are hereby corrected as shown below:

I" Column 6, line no should read R R z C (CH CH) 1 C S/ w-w UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Potent No. 3566655 Dated Anril 1 1970 Inventoth) Roy A- Jeffreys L PAGE 3 It is certified that error appears in the above-identified patent end that said Letters Patent are hereby corrected n shown below:

[ Column 6, line 75 R /CHR R3 NC\ should read N R CH R R CH R Column 7, line 39 should read Po-wso I UNITED STATES PATENT OFFICE CERTIFICATE 0 CORRECTION Patent No. 3506655 Dated April 1.4 1970 Inventorh) ROY A- Jeffreys I PAGE 4 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

r- Column 7, line +8 "any invention" should be changed to my invention Column 8, line 37 should read mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION 3506655 Dated April 14, 1970 Patent No.

Inventofls) ROY A. Jeffreys PAGE 5 It is certified thsterror appears in theabove-identified patent and that said Letters Patent are hereby corrected as shown below:

I Column 9, lines 20-22 "was filtered 0c from the chilled solution. After several recrystallizations fro methanol it wacs obtained as bright blue prime,"

should read:

-- was filtered off from the chilled solution. After 2 several recrystallizations from methanol it was obtained as bright blue prisms,

Column 3 line 6 "Z represents the non-metallic atom necessary to complete" should read:

- Z represents the non-metallic atoms necessary to complete Signed and sealed this 8th day of September 1970 (SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR.

Commissioner of Patents Attesting Officer 

